So-called incremental rotary encoders are known for the sensing of rotation angles, for example in conjunction with electrical machines. These encoders convert the input variable, namely the rotation angle of, for example, a rotor, into a number of electrical pulses. The conversion can be achieved, for example, by optoelectronic scanning means of a rotary disk having radial transparent slots. The number of such slots defines the resolution (pulses per revolution). Incremental encoders of this kind serve, for example, to ascertain a rotation angle within a rotation range from 0 to 360 degrees. If it is desired to sense rotations beyond 360 degrees, so-called multi-turn transducers (absolute value transducers) are then known. These encompass further coding disks in addition to the coding disk for sensing the angular position, so that revolutions beyond 360 degrees can also be sensed.
So-called resolvers are also known for the sensing of rotary motions. By means of a resolver, the absolute position of the motor shaft is ascertained. The resolver is made up of a rotor coil and two stator windings offset 90 degrees from one another, and operates on the principle of the rotary transformer. The resolver additionally has a respective auxiliary winding in the stator and on the rotor, to ensure brushless voltage supply. Voltages of different magnitudes are induced in the stator windings depending on the position of the rotor. The voltages at the two stator windings are modulated in transformer fashion by the supply voltage, and have sinusoidal envelope curves. The two envelope curves are offset 90 degrees electrically from one another, and are evaluated in the inverter as to zero transition and amplitude. The absolute rotor position, rotation speed, and rotation direction can thereby be ascertained.
The aforementioned so-called transducer systems are based on a wide variety of principles and require a wide variety of control systems and furnish a wide variety of signal shapes. Each transducer type therefore requires an interface specific to it. German Application DE 34 456 17 A1, for example, describes a method and an arrangement for serially transferring the digital measured values of a measured-value converter by means of an interface relevant to the transducer described therein. For transfer of the digital measured values of a measured-value converter, in particular of an angular encoder or a linear measurement encoder, the measured values (occurring in parallel) are stored in a parallel-serial shift register and transferred serially in synchronism with a clock-timed pulse train that is generated by a processing unit that receives the measured values. This synchronous and serial transfer enables simple processing of the transferred data, and a high baud rate for the data transfer.
It is easy to recognize that the manner of operation explained in conjunction with the aforementioned German Application deviates, for example, from the previously explained manner of operation in conjunction with the resolver.
So-called drive control devices or drive amplifiers are required for the application of control to electrical machines, in particular to electrical servomotors. Said devices supply a rotary current motor with, for example, a three-phase current, and simultaneously regulate position and rotation speed utilizing the aforementioned measured-value converter signals. The measured-value converters that are in turn required for this are arranged on the rotating or moving part of the motor. When a measured-value converter of this kind is used by the device, the entire arrangement is then in a so-called closed-loop operating mode. A closed control circuit therefore exists, and the device continuously processes the signals generated by the measured-value converter in the context of control application to the electrical servomotor.
A large number of measured-value converter variants exist in the automation sector. The manufacturers of automation components endeavor to support as many measured-value converter types as possible. The problem thus exists that, in order to support as many measured-value converters as possible, a drive control unit or a drive amplifier would need to have a correspondingly large number of measured-value converter interfaces. This in turn requires increased hardware complexity and increased software outlay. Operation also becomes more complex, since the correct converter must be manually configured by the setup technician upon initial setup. In order to avoid this outlay, it would be possible to make available different drive controller variants or drive amplifiers that are tailored for specific measured-value converter types. This would, however, result in a great multiplicity of variants and versions, which is not desired by manufacturers because of the cost outlay associated therewith. In addition, the outlay on the part of customers of the component manufacturer would thereby also rise, since the aforementioned multiplicity of variants would need to be taken into consideration and managed in terms of configuration and scheduling.